What indicates a problem if FADEC aborts the start of an engine?

When the Full Authority Digital Engine Control (FADEC) system aborts the start of an engine, it typically does so to protect the engine from potential damage. The correct reasoning for option C being the appropriate explanation relates directly to the parameters that FADEC monitors during the start sequence.

FADEC is designed to ensure that the engine operates within safe and recommended limits. If there is an over-temperature condition detected, it can indicate that the engine is getting too hot during the start process, perhaps due to a malfunction or an issue with the fuel-air mixture. Similarly, inadequate fuel supply can lead to abnormal combustion characteristics, affecting the engine's performance and stability. Consequently, FADEC will abort the start to prevent damage from occurring in these scenarios.

In contrast to option C, the other options provide scenarios that may contribute to performance issues but are not directly the primary reasons for a FADEC-initiated abort during engine start. While fuel pump failure, excessive vibration, and lack of engine rotation can all indicate problems during engine operation, they are related to different operational conditions rather than the specific triggers that would cause FADEC to abort an engine start due to temperature and fuel supply concerns.